1. Field of the Invention
Method and arrangement for taking up a first medium, which is present in a first phase, into a capillary device
2. Description of the Related Prior Art
An arrangement disclosed by [1] has a microtitre plate with a plurality of wells for taking up an analyte.
Such a microtitre plate is used, for example, for a wide variety of applications in medicine and biotechnology for taking up liquids to be analysed, for example in the field of DNA analysis.
Usually, a different analyte to be analysed is introduced in each well and via a pipette, usually via a plurality of adjacently arranged elements designed as a so-called pipette comb; in a pipette comb, for example, a respective pipette is provided for each well in a row of the microtitre plate, which has wells arranged in an array.
By means of a pipette, an analyte is in each case withdrawn because of a reduced pressure created in the pipette, i.e. it is sucked up, from the corresponding well which is filled with the analyte and into which the pipette is dipped.
According to the arrangement known from [1], the pipette is in each case coupled, via tubing, to a pump which is assigned uniquely to the respective pipette, and which produces the reduced pressure, in such a way that the analyte can be sucked through the corresponding pipette by means of the pump and correspondingly can in turn be introduced into the well while being controlled by the pump.
Such a known microtitre plate has, for example, 96 wells with a size of 8 cm H 12 cm.
Such a known microtitre plate, however, may in principle have any desired number of wells, usually up to 384.
A particular disadvantage of the arrangement known from [1] is that, because of the high number of pumps, it is impractical or sometimes impossible to provide a separate pump on such a small area of 8 cm H 12 cm for each well in a row, i.e. for such a large number of pipettes.
The production of such a pipette comb, and hence of such an arrangement for taking up liquid analytes, is therefore very demanding and expensive.
It should furthermore be pointed out that, in the arrangement known from [1], a peristaltic pump is normally used in each case for sucking the analyte out of the well in question and for introducing it therein.
A considerable disadvantage of this known arrangement is furthermore that a minimum amount of an analyte to be analysed, of the order of 1 ml, is needed for the analysis.
Another disadvantage is that the large number of pumps required, with the associated tubing arrangement, is very complicated and therefore susceptible to faults.
Furthermore, [2] describes a so-called Flow-Thru Chip™, by means of which analysis of the analyte with respect to the existence of biological material in the analyte is possible.
The Flow-Thru Chip™, which is a configuration of an analysis chip, has a plurality of channels through which the analyte is fed through the analysis chip, the surface of the channels being provided respectively with probe molecules, generally with molecules which can bind, preferably covalently, the correspondingly targeted biological material whose existence in the analyte is to be detected.
If the biological material in the analyte is a DNA strand with a predefined DNA sequence to be determined, then DNA probe molecules with a sequence complementary to the DNA sequence to be determined are applied to the surface of such a liquid channel in the Flow-Thru Chip™.
If the DNA material with the targeted DNA sequence is present in the analyte, then the DNA strands bind with the corresponding DNA probe molecules of opposite, i.e. complementary sequence.
In general, such an analysis chip is often used for the analysis, i.e. for the detection of macromolecular biopolymers, examples of which include proteins or peptides as well as DNA strands with a respective predefined frequency.
Furthermore, [3] discloses the production, from glass or silicon, of a diaphragm which has a plurality of pores with a constant diameter of from 0.1 Fm to 1 Fm.
It is therefore an object of the invention to take up a first medium present in a first phase, for example as a liquid or as a gas, into a capillary device, the take-up being carried out more simply and less expensively compared with the prior art.
The object is achieved by the method and the arrangement having the features according to the independent patent claims.
In a method for taking up a first medium, which is present in a first phase, into a capillary device, a reduced pressure is produced in the capillary device. The first medium is taken up into the capillary device by the reduced pressure.
The first medium may be present as a liquid or as a gas.
For example, the first medium may be a liquid to be analysed, i.e. an analyte that will be analysed by using the capillary device and an analysis chip, which is coupled to the capillary device and with which the taken-up first medium is brought into contact.
In this case, the analysis chip is, for example, the Flow-Thru Chip™ described in [2]; biological material may be contained in the liquid channels of the analysis chip and applied to the surface of the liquid channels, the biological material being designed in such a way that biological molecules contained in the first medium can be bound by probe molecules.
For instance, DNA probe molecules may be applied as biological material to the liquid channels in order to bind DNA strands which are contained in the analyte and have a DNA sequence that is complementary to the sequence of the DNA probe molecules.
The invention ensures that the reduced pressure produced in the capillary device is less than a critical pressure such that, if it is exerted in the capillary device, a surface tension which is produced by the first medium or a second medium, which is described below, in the capillary device, when the first medium has been taken up fully by the capillary device, would be overcome.
This prevents the second medium, which is present in a second phase which is different from the first phase, from being taken up into the capillary device after the first medium has been taken up fully.
Clearly, this means that in the capillary device, for example by means of a pump controller which controls a pump producing the reduced pressure in the capillary device in such a way that the reduced pressure, which is produced in the capillary device, is set in such a way that the reduced pressure does not exceed the surface tension of the first medium or, if e.g. the first medium is present in gas form and the second medium is present as a liquid, of the second medium in the capillary device.
The critical pressure in the capillary device is given, for example, by the following rule:
      P    =          2      ·              S        r              ,where